JPH0693426B2 - Lithography mask structure and photolithography processing method using the same - Google Patents

Description

The present invention relates to a mask structure used in lithography. Such a mask structure is used, for example, in manufacturing a semiconductor device. Furthermore, the present invention relates to a photolithography processing method using a mask structure.

[Prior Art] It is widely used industrially, particularly in the field of electronics, to manufacture various products by partially modifying the surface of a work material by using a lithographic technique. A large amount of products having the same surface alteration can be manufactured. The alteration of the surface of the material to be processed is carried out by irradiation with various energy rays. At this time, a mask in which an energy ray absorbing material is partially arranged is used for pattern formation. As such a mask, when the irradiation energy ray is visible light, a black paint is partially applied on an illuminating substrate such as glass or quartz, or a visible light absorbing thin plate of metal such as Ni, Cr. Alternatively, a thin film partially provided has been used.

However, in recent years, along with the demand for finer pattern formation and the demand for a lithography processing technique in a shorter time, X-rays and particle beams such as ion beams have come to be used as irradiation energy rays. Most of these energy rays are absorbed when passing through the glass plate or the quartz plate used as the mask forming member in the case of the visible light. Therefore, when using these energy rays, it is not preferable to form the mask using a glass plate or a quartz plate. Therefore, in the lithographic processing technique using X-rays or particle beams as irradiation energy rays, various inorganic thin films such as silicon nitride, boron nitride, silicon oxide, titanium, etc., or various organic thin films such as polyimide, polyamide, or A thin film of polyester or the like, or a laminated film thereof is used as an energy transmitting body, and a metal such as gold, platinum, nickel, tungsten, palladium, rhodium or isodium is partially provided as an energy ray absorber on these surfaces. By
Forming a mask is performed. Since this mask does not have self-shape retention, it is supported by an appropriate holder. As a mask structure constructed in this way, a mask structure shown in the sectional view of FIG. 7 has been conventionally used. This is because the energy ray-absorbing mask material 1 is applied on one side in a desired pattern to the peripheral portion of the energy ray-transmitting holding thin film 2 on one end surface (the upper end surface in the figure) of the annular holding substrate 3 with an adhesive. It was formed by sticking using 4. Incidentally, FIG. 8 is a plan view of the holding substrate 3.

By the way, when performing the photolithography process using the above-described mask structure, the mask pattern of the mask structure is accurately measured with respect to the work material such as a silicon wafer (the surface of which is coated with photoresist). It is necessary to perform the alignment (alignment) and to accurately set the gap (gap) between the surface of the workpiece and the mask material holding thin film of the mask structure.

Therefore, in the conventional lithography process using a mask structure, marks for alignment are provided on the surface of the work material and the holding thin film of the mask structure, and the holding thin film is placed after being substantially parallel to each other. Alignment is performed by irradiating a visible light beam from the side while detecting the degree of matching of both marks, and the gap is set while detecting the reflected light on the surface of the holding thin film and the reflected light on the surface of the workpiece. It was

However, in such detection, visible light transmitted through the holding thin film is detected, so that the detection accuracy is lowered due to scattering and / or absorption in the holding thin film, and the photon of sub-micron order or less is detected. It is not possible to obtain sufficient alignment and gap setting accuracy in lithography.

Further, in order to improve the detection accuracy of the alignment mark, it is possible to use electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays instead of visible rays, but these are significantly scattered and absorbed by the holding thin film. So virtually unusable.

[Object of the Invention] In view of the above-mentioned conventional techniques, it is an object of the present invention to provide a lithographic mask structure capable of performing alignment with a work material and setting a gap with high accuracy. A further object of the present invention is to provide a photolithography processing method using the mask structure as described above.

[Summary of the Invention] According to the present invention, for achieving the above-mentioned object, for lithography in which a peripheral portion of a mask material holding thin film to which a mask material is to be applied in a desired pattern on a surface is held by a holding substrate. In the mask structure, the mask material holding thin film is provided with a plurality of through holes through which energy rays for detecting the alignment state with the workpiece can be passed, and the through holes correspond to the scribe line of the workpiece. There is provided a mask structure for lithography, which is provided at a position where

Further, according to the present invention, in order to achieve the above object, a mask structure for lithography in which a peripheral portion of a mask material holding thin film having a mask material applied in a desired unit pattern on the surface is held by a holding substrate. Through the body, a work material having a plurality of regions divided by scribe lines was irradiated with a first energy ray, and the plurality of regions were applied to the mask material holding thin film of the mask structure. A photolithography processing method for transferring a unit pattern, wherein the mask structure is provided with a plurality of through holes at positions corresponding to scribe lines of the material to be processed in the mask material holding thin film, Two
Of the energy beam of the mask structure is passed through a through hole provided in the mask structure to detect an alignment state between the mask structure and the workpiece, and the relative positions of the mask structure and the workpiece are associated with each other. After that, a photolithography processing method is provided, which comprises irradiating the first energy beam.

[Embodiment] FIG. 1 shows a plan view of a specific example of the mask structure for lithography according to the present invention. Fig. 2 shows II- in Fig. 1.
FIG. 2 is a sectional view taken along line II (however, FIG. 1 and FIG. 2 do not completely match). This specific example is a mask structure for X-ray photolithography.

The mask material 1 is applied to one surface of the holding thin film 2 in a desired pattern. As the mask material 1, for example, a thin film of about 0.5 to 0.7 μm such as gold, platinum, nickel, tungsten, tantalum, copper, molybdenum, palladium or rhodium can be used.

The peripheral portion of the holding thin film 2 is adhered to the annular holding substrate 3 with the adhesive 4 in the stretched state.

As the holding thin film 2, an organic thin film of polyester, polyamide, polyimide, parylene, or an inorganic thin film of silicon nitride, boron nitride, silicon oxide, or the like can be used. The thickness of these thin films 2 is, for example, about 2 to 20 μm.

The holding thin film 2 is bonded to the holding substrate 3 in an isotropically stretched state at a stretching ratio of, for example, about 5 to 20% (area ratio).

As the holding substrate 3, for example, silicon, glass, quartz, phosphor bronze, brass, iron, nickel, stainless steel or the like is used.

As the adhesive 4, for example, an epoxy type, a rubber type, or other appropriate type is used, for example, a solvent type, a thermosetting type, or a photocuring type.

The holding thin film 2 is provided with a plurality of small holes 5 (four in the figure) that penetrate from the front surface to the back surface at positions where the mask material 1 is not applied.

The shape of the small holes 5 is not particularly limited, and may be square, rectangular, rectangular, triangular, hexagonal, octagonal, or other square, circular,
The shape may be any of a round shape such as an elliptical shape and a shape of a combination thereof, but a circular shape is particularly preferable from the viewpoint of preparation. The size of the small hole 5 is not particularly limited, depending on the alignment with the target workpiece, the state of the gap, the type of energy ray used for detection, and the required detection accuracy, etc. It can be set appropriately. Examples of energy rays used for detection include electron beams, ion beams, X-rays, ultraviolet rays, and vacuum ultraviolet rays, and visible rays and infrared rays can also be used. As an example, when the detection is performed using an electron beam, the diameter of the small hole 5 is about 10 to 30 μm.
Two or four small holes 5 are provided axially symmetrical with respect to the axis of symmetry of the annular holding substrate 3. However, the position where the small hole 5 is provided is appropriately set according to the pattern of the mask material 1 in the mask structure.

In the photolithography process such as a semiconductor device manufacturing process, as shown in FIG. 3, a large number of semiconductor devices 11 having the same pattern are formed on a semiconductor wafer 10 as a workpiece. These semiconductor elements 11 are cut into boundary lines (scribe lines) 12 after forming a pattern to be each semiconductor element chip.

In such a photolithography process, as the pattern of the mask material 1 of the mask structure, a pattern in which a plurality of unit patterns of the semiconductor element are arranged in parallel is used. In FIG. 1, the unit pattern 7 of the semiconductor element is 4
Individually arranged. These unit patterns 7 are
The line 8 is divided by the line 8 corresponding to the scribe line 12 of the semiconductor wafer 10. In photolithography, the predetermined scribe line 12 of the semiconductor wafer 10 and the corresponding line 8 of the mask structure 13 are accurately associated with each other. Alignment is performed (see FIG. 4), and then energy rays such as X-rays are irradiated. And
Further, the relative positions of the semiconductor wafer 10 and the mask structure 13 are changed, and the unirradiated semiconductor element group is subjected to alignment and energy ray irradiation in the same manner as above, and this is repeated.

The semiconductor wafer 10 is provided with alignment marks formed as, for example, recesses at appropriate positions on the scribe line 12 by etching or the like. Like this
When the alignment mark is formed on the scribe line 12 of the semiconductor wafer 10, the small hole 5 in the mask structure has a line corresponding to the scribe line corresponding to the alignment mark as shown in FIG. 8 is formed. The scribe line of the semiconductor wafer 10
12 has a width of, for example, about 30 μm, and the alignment mark is formed with a size smaller than that. In this case, it is preferable that the small hole 5 has a diameter of about 15 μm.

The method of forming the small holes 5 in the holding thin film 2 is appropriately selected according to the material of the holding thin film 2. For example, a method using a laser beam (excimer laser, argon laser, etc.), a method using dry etching (RIE oxygen plasma, etc.) Examples thereof include chemical etching (hydrazine-based etchant, etc.) and mechanical means (milling, etc.). Two or more of these methods may be used in combination.

The small holes 5 are preferably formed in a step close to the final step of the mask structure, which can prevent the small hole position accuracy from being deteriorated due to post-processing.

Good patterning accuracy can be realized by performing pattern formation for forming small holes at the same time as the step of forming the mask material 1 on the holding thin film 2.

As shown in FIG. 5, the mask structure 13 as described above is
At the time of use, it is used in close proximity to the semiconductor wafer 10. A resist layer 14 is formed on the surface of the semiconductor wafer 10. While moving the mask structure 13 in the left-right direction relative to the semiconductor wafer 10, the small holes 5 are irradiated with an electron beam from above to detect secondary electrons generated from the semiconductor wafer 10. At this time, the detection value of the secondary electrons differs depending on the presence or absence of an alignment mark (for example, a concave portion as shown in the figure), and the arrangement when the detection value takes an extreme value is arranged on the mask structure 13 with respect to the scribe line 12 of the semiconductor wafer. The small holes 5 are accurately arranged. By similarly detecting the plurality of small holes 5, the relative positional relationship between the semiconductor wafer 10 and the mask structure 13 can be made accurate. Similarly, when measuring the gap, the electron beam that has passed through the small hole 5 is measured. Of course, a method of detecting focus shift by an optical lens can also be used.

In addition to the above-mentioned electron beam, an ion beam, an X-ray, etc. may be used as an energy ray used for alignment or detection of a gap when the mask structure of the present invention is used.
Lines, ultraviolet rays, vacuum ultraviolet rays, and also visible rays and infrared rays can be used, and if the alignment mark on the side of the material to be processed is formed to show a behavior different from those of the surrounding energy rays. Good.

In the mask structure of the present invention, it is also possible to use a laminated film in which two or more thin films are laminated as the mask material holding thin film.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1: A mask structure having a vertical sectional view shown in FIG. 6 was prepared.
In FIG. 6, members similar to those in FIG. 2 are designated by the same reference numerals. In this embodiment, no adhesive is applied to the upper flat end surface 3a of the annular holding substrate 3,
An adhesive 4 is applied to the slope 3b on the upper outer side, whereby the holding thin film 2 and the holding substrate 3 are bonded. It is suitable that the angle θ of the inclined surface is about 5 to 15 degrees, and in this embodiment, it is set to 10 degrees.

According to such a mask structure of this embodiment, the mask material holding plane of the holding thin film 2 is not affected by the adhesive 4 and realizes a good flatness of the flatness of the upper flat end surface of the holding substrate 3 as it is. It is possible to improve the accuracy of lithography processing.

First, a polyimide film (thickness of 7.5 μm, isotropically stretched with an adhesive 4 to the annular holding substrate 3 at a stretch ratio of about 10%.
The product name Kapton film) was adhered.

Next, a photoresist AZ-1350 (manufactured by Shipley Co., Ltd.) was applied on the holding thin film to a thickness of 0.5 μm under the specified conditions, and a resist with two small holes of about 15 μm in diameter was made by a quartz mask using a deep UV baking machine. A pattern was formed.

Next, the polyimide film at the small hole pattern position was removed by etching to form small holes.

Based on the two small holes formed in this way, the electroforming method is used to perform a predetermined process on the holding thin film.
An X-ray absorption pattern consisting of a 0.5 μm gold film was formed.

Example 2 In Example 1, the X-ray absorption pattern made of a gold film having a thickness of 0.5 μm was formed on the holding thin film by an electrohoming method in a predetermined process without etching the polyimide film.

After that, an excimer laser is intensively radiated on the basis of the pattern, and two diameters of about two diameters are provided on the line corresponding to the scribe line.
Small holes of 15 μm were formed.

Example 3: In Example 2, small holes were similarly formed by using an argon laser instead of the excimer laser.

Example 4: A small hole was formed in the same manner as in Examples 2 and 3 using a polyester film (6 μm thick, Lumirror, manufactured by Toray Industries, Inc.) instead of the polyimide film.

Example 5: Using a polylimide film as a holding thin film, when forming a mask pattern made of a gold film, a small hole pattern having a diameter of about 10 μm was provided in the gold film on the line corresponding to the scribe line at the same time. Only a hydrazine-based etchant was dropped to form two small holes in the polyimide film in a dozen seconds.

[Advantages of the Invention] According to the present invention as described above, in the lithography process, when the mask structure is aligned with the workpiece and the gap is set, the energy beam irradiation is performed through the through hole provided in the mask material holding thin film. By doing this, it is possible to detect the reflection from the work material with little scattering and absorption, so that it is possible to perform alignment and gap setting with high accuracy, thereby enabling highly accurate lithography processing. You can Further, according to the present invention, since the through hole is provided at the position corresponding to the scribe line of the workpiece, there is an advantage that the alignment mark can be easily created and the alignment can be easily performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a mask structure of the present invention, and FIG. 2 is a II-II sectional view thereof. FIG. 3 is a partial plan view of the work material, and FIG. 4 is a partial cross-sectional view showing the relationship between the work material and the mask structure. FIG. 5 is a partial cross-sectional view showing a usage state of the mask structure of the present invention. FIG. 6 is a sectional view of the mask structure of the present invention. FIG. 7 is a sectional view of a conventional mask structure, and FIG. 8 is a plan view of its holding substrate. 1: Mask material, 2: Holding thin film 3: Holding substrate, 4: Adhesive 5: Small hole 8: Line corresponding to scribe line 10: Work material, 12: Scribing line 13: Mask structure, 14: Resist layer

Claims (9)

[Claims] 1. A lithography mask structure in which a peripheral portion of a mask material holding thin film to which a mask material is applied on a surface in a desired pattern is held by a holding substrate, and the mask material holding thin film is aligned with a workpiece. A mask for lithography, characterized in that a plurality of through-holes through which energy rays for detecting a state can be provided, and the through-holes are provided at positions corresponding to scribe lines of a workpiece. Structure. 2. The mask structure for lithography according to claim 1, wherein the energy beam is an electron beam. 3. The energy beam is an electron beam, and the diameter of a through hole provided in the mask material holding thin film is 10
The first aspect of the present invention is characterized in that
The mask structure for lithography according to the item 1. 4. A lithographic mask structure in which a peripheral portion of a mask material holding thin film having a mask material applied in a desired unit pattern on its surface is held by a holding substrate,
The work material having a plurality of regions divided by the scribe line is irradiated with the first energy ray, and the unit pattern given to the mask material holding thin film of the mask structure is transferred to the plurality of regions. A photolithography processing method, wherein the mask structure is provided with a plurality of through holes at positions corresponding to scribe lines of the material to be processed in the mask material holding thin film, and a second energy ray is used. After detecting the alignment state of the mask structure and the workpiece by passing through the through hole provided in the mask structure, after making the relative positions of the mask structure and the workpiece correspond, Irradiating with the first energy ray, a photolithography processing method. 5. The alignment state is detected by detecting the reflection of the second energy beam, which has been passed through a through hole provided in the mask structure, from a material to be processed. The photolithography processing method according to claim 4. 6. The photolithography processing method according to claim 4, wherein the first energy rays are X-rays. 7. An alignment mark is formed at a predetermined position on a scribe line of the material to be processed, and a through hole provided in the mask structure is formed corresponding to the alignment mark. The photolithography processing method according to claim 4, which is characterized in that. 8. The photolithography processing method according to claim 4, wherein the second energy beam is an electron beam. 9. An alignment mark is formed at a predetermined position on a scribe line of the work material, and a through hole provided in the mask structure is formed corresponding to the alignment mark. An electron beam as a second energy ray is passed through a through hole provided in the mask structure to irradiate a scribe line of a corresponding work material to detect a secondary electron, and the secondary electron is detected. A fourth aspect of the present invention is characterized in that the relative positions of the mask structure and the workpiece are made to correspond to each other according to the value.
The method of photolithography according to item.